9514 1404 393
Answer:
535.43 cm²
Explanation:
The area of an equilateral triangle is ...
A = (√3)/4s² . . . . where the side length is s
For a side length of 8 cm, the area of each of the triangular surfaces is ...
A = (√3)/4×(8 cm)² = 16√3 cm²
Each of the rectangular faces is 8 cm wide and 20 cm long, so their total area is ...
LA = 3(8 cm)(20 cm) = 480 cm²
The total surface area is the sum of the areas of the two bases and the lateral area:
SA = LA +2A = 480 cm² +2(16√3) cm² = (480 +32√3) cm²
SA ≈ 535.43 cm²